Continuous treatment of wool to shrinkproof and sensitize the same



United States Patent 3,098,694 CONTINUGUS TREATMENT OF WOOL T0 SHRINK-PROOI? AND SENSTTIZE THE SAME Malcolm J. Render, Shillington, Pa.,assignor to Drew Chemieal Corporation, a corporation of Delaware NoDrawing. Filed July 11, 1960, Ser. No. 41,760

14 Claims. (Cl. 3-128) into garments, for example, and they may causeundesira'ble shrinkages in the garments, causing them to get out ofshape. Methods have been proposed to prevent such relaxation and millingor felting shrinkage but they had the defect of being batch processeswhich interfered with the conduct of other treatments normally conductedon such (fabrics.

The present invention is intended and adapted to overcome thedeficiencies of the prior art, it being among the objects of theinvention to provide a substantially continuous method of treating woolfabrics to stabilize the same against relaxation shrinkage, milling andfelting.

It is also among the objects of the invention to provide a process whichwill sensitize the fabric and stabilize it without interfering withnormal treatments.

It is [further among the objects of the invention to provide a processwhich is operable in a much shorter time than prior processes of thistype, thereby rendering the process more economical.

It is still further among the objects of the invention to devise aprocess in which the shrinkproofing materials are not critical in theproportions thereof used in the oporation.

In practicing the invention the wool fabric is passed through a bathcontaining a strong acid, such as sulfuric in order to deposit on or inthe wool, either in combination or physically, a substantially amount ofthe acid. The content of acid is important and it is present on the woolin amounts of about 2.5% to 15%, the preferred range being 5% to 12% onthe Weight of the Wool. In the next step the fabric is passed through amixture in solution of bromate and halide in which the relativeproportions of the salts may be varied widely With good results. Awetting agent inert to halogen is used to facilitate the treatment, suchagents being, for example, condensation products of ethylene oxide andoctylor nonyl-phenols. The excess acid is neutralized, as with sodiumbicarbonate, While leaving the Wool still on the acid side. Then thefabric is treated with an aqueous solution of an alkali metal sulfite orbisulfite in suflicient amount to neutralize the free bromine plus anamount suflicient to reduce the disulfide linkages in the W001, which isthen dried. The wool is then in a sensitized condition.

The [thus sensitized fabric may be dried at a temperature below about175-l 80 to retain its sensitiveness. A garment may be made therefromand permanent creases or pleats may be formed therein by subjecting thegarment to temperatures above about 175-180 F., as in the standard steampressing machine to set the fabric. If the drying is conducted at thesehigher temperatures in the piece, while the fabric is held flat andsmooth, then the fabric will be smooth, creaseless and not sub- "Iceject to further shrinkage or felting; and garments made therefrom willretain their shapes through many cleanings or washings. If the drying isat or above 175-180 F. only about two minutes treatment are required sothat the total fabrictreatment may be continuous. At temperatures of,say, 140-150 F. as much as 10 to 15 minutes are required for the dryingoperation.

The following is a specific example of the operation of the invention:

The fabric to be treated is passed through a solution of 14% sulfuricacid in water, plus a small amount of wet-out material such as thecondensation product of ethylene oxide and octyl phenol. The temperatureof the sulfuric acid solution is maintained between and F. to assist inrapid wetting and combination of the wool with the sulfuric acidpresent.

The fabric is then squeezed in a pad machine to a pickup of 75%. With apickup of 75% of a 14% solution of sulfuric acid, the net result beingthat the fabric contains 10% of its Weight of sulfuric acid. In theevent that a squeeze is used that leaves a different amount of liquor onthe fabric, the initial concentration of sulfuric acid should be variedso that the fabric on leaving the pad actually contains 10% of itsweight of sulfuric acid.

The fabric is then passed through a solution consisting of 2% potassiumbromate and 7% potassium bromide. This is actual solution percentage.The temperature of this solution is maintained at 120 to .F. and theacidified fabric on passing through this bath is again squeezed toapproximately 75% pickup. The fabric thus treated is then held for aperiod of two minutes to permit the reaction between the freed bromineand the wool to take place. This time delay can be achieved by skyingthe goods or holding it in a J box for this length of time.

The fabric is next passed through a washer or other suitable unitcontaining a solution of sodium bicarbonate and sodium sulfitesuflicient to neutralize the excess acid and the free halogen. A 3%solution of sodium bicarbonate containing /2% of sodium sulfite issuflicient for this purpose. The temperature of this solution is about120 to 140 F. Instead of the potassium bromate-potasslum bromide statedabove, 2% potassium bromate and 12% sodium chloride may be used toeifect the same shrinkproofing reaction.

After passing the treated fabric through a clear water solution to washout soluble salts, and squeezing, it is now ready for finishing in theusual manner and is now shrinkproofed. It is most expeditious to performthis treatment immediately after an acid fulling or milling operationhas been completed. Milling or fully of any type will not be effectiveon the goods after shrinkproofing has been applied.

The stabilization of the fabric involves the reduction of the disulfidelinkages in the wool molecules by sodium bisulfite solution to produce asensitized fabric. That is, a fabric that upon being subjected tosteaming and/or heating in a fixed position will tend to remain in thatfixed position. As an example: the steam pressing of sensitized fabricin a steam press to create a crease as in trousers or pleated skirtsthat Will be permanent and withstand laundering in the ordinaryhome-type washer.

In the present process, immediately after the application of the bromateand bromide solution, the fabric is treated with sodium bicarbonate toneutralize the traces of remaining acids, and in addition, a sufficientamount of sodium sulfite is added to neutralize any free halogen thatmight be present and react with the wool to reduce disulfide linkagesand to perform the sensitizing reaction as well.

For example, the fabric is passed into a 2% sodium bicarbonate solution,or an amount of bicarbonate sufficient to maintain a pH of 5.0 on thefabric. To this same sodium bicarbonate solution is added 3% of sodiumsulfite. It is necessary that the amount of bicarbonate added to thisamount of sulfite is such that the fabric will when passing through thesensitizing bath, and after being squeezed, have a pH of 5.0:05. Thetemperature of this solution is held at about 140 F. and the goodsremain in the bath for a few seconds. The excess solution is thensqueezed from the fabric and the fabric is held for about minutes tocomplete the sensitizing reaction. At the end of 5 minutes the fabric iswashed in water no hotter than about 125 F. and squeezed. At this pointthe fabric is sensitized and ready for further processing by one of twomethods.

Method N0. 1 for Utilizing Sensitized Fabric If the fabric is dried at atemperature below 180 F. with plenty of moving air to facilitate'therapid drying, it will be in a condition wherein it can accept a creaseby pressing on a steam press for approximately 30 seconds using a damppress-cloth and steam of 60 pounds pressure. After pressing and allowingto air dry for a period of 24 hours, this crease will be permanent andwill withstand repeated laundering in a home-type Washer. At no timeprior to the pressing of the pleats or creases must the fabric, that hasbeen sensitized, be permitted to reach a temperature in excess of 180F., especially in the presence of steam. If this is allowed to happenthe cloth will lose its sensitivity and be unable to undergo a permanentcreasing or pleating operation.

Method N0. 2 for Utilizing Sensitized Fabric The sensitized wet fabricmay be subjected to a stabilizing treatment by passing it while stilldamp over a series of drying cans or large mangles until it is ironeddry with no added tension being placed upon the fabric.

Instead of drying cans, the goods can be fed while still damp onto asemi-decator, a crab, tenter-frame or other similar device designed tosteam the goods in a fixed fiat controlled position. Fabric that [hasbeen treated in this Way is then dried in a conventional dryer at usualtemperatures using over-feed so as to introduce no tension, and finishedin the usual manner.

Another method of producing the stabilized fabric is to dry the goods ata temperature below 180 F., again with an abundance of moving air, andthen subjecting the fabric to the normal shearing, cropping, napping,lustering, polishing and/or other dry finishing processes, being carefulto avoid any process that would introduce heat in the order of 175--l8'() F. The fabric in a sensitized condition, while being given thispreliminary finishing treatment, should not be subjected to a steamingoperation. After the preliminary finish has beenv applied, the fabriccan then be wound onto a decating device and subjected to the usualdecating process. Or in the case of developing a polished or high lusternap, a heated polishing roll or iron may be used to simultaneouslypolish and set the fabric.

In the claims the use of the term wool is intended to include allkeratinous fibers amenable to the process.

What is claimed is:

1. A continuous method of treating wool to shrinkproof and sensitize thesame which comprises- (1) passing'said wool through a bath of an aqueoussolution of an acid and depositing on said wool about 2.5% to 15% ofsaid acid based on the weight of said wool,

(2) then passing said wool through an aqueous solution of an alkalimetal bromate and an alkali metal salt of an acid radical taken from theclass consisting of bromide and chloride,

(3) thereafter neutralizing excess of acid while leaving said wool onthe acid side, and

(4) subsequently passing said wool through an aqueous solution of asubstance taken from the class consisting of alkali metal sulfite andbisulfite (5) and at a temperature not over about 175 F. to

sensitize said wool.

2. A method according to claim 1 wherein the sensitized wool is dried attemperatures below about 175 F.

3. A method according to claim 1 wherein the sensitized wool is dried attemperatures above about 175 F. to stabilize said wool in a current ofsteam.

4. A method according to claim 1 wherein the amount of acid carried bysaid wool is about 5% to 12%.

5. A method according to claim 1 wherein the temperature of said acidtreatment is about to F.

6. A method according to claim 1 wherein the wool picks up about 75% ofa 2% bromate solution.

7. A method according to claim 1 characterized in that the temperatureof bromination and of sulfiting is about 120-140 F.

8. A method according to claim 1 wherein the neutralization is to a pHof about 4.5 to 5.5.

9. A method according to claim 1 wherein the ratio of bromate to halideis from 1-4 of bromate to 8-1 of halide, respectively.

10. A method according to claim 1 wherein a wetting agent resistant tohalogenation is employed.

11. A method according to claim 1 wherein an excess of said sulfite ispresent in sufficient amount to reduce sulfide linkages to sensitize thewool.

12. A method according to claim 1 wherein the amount of said sulfite issufficient to neutralize free bromine but insuflioient to sensitize saidwool.

13. A method according to claim 1 wherein the sensitized wool is driedat temperatures above about F. to stabilize said wool.

14. A method according to claim 13 wherein the wool in the form offabric is under stress during said stabilization.

References Cited in the file of this patent UNITED STATES PATENTS LevinFeb. 2, 1960

1. A CONTINUOUS METHOD OF TREATING WOOL TO SHRINKPROOF AND SENSITIZE THE SAME WHICH COMPRISES(1) PASSING SAID WOOL THROUGH A BATH OF AN AQUEOUS SOLUTION OF AN ACID AND DEPOSITING ON SAID WOOL ABOUT 2.5% TO 15% OF SAID ACID BASED ON THE WEIGHT OF SAID WOOL, (2) THEN PASSING SAID WOOL THROUGH AN AQUEOUS SOLUTION OF AN ALKALI METAL BROMATE AND AN ALKALI METAL SALT OF AN ACID RADICAL TAKEN FROM THE CLASS CONSISTING OF BROMIDE AND CHLORIDE, (3) THEREAFTER NEUTRALIZING EXCESS OF ACID WHILE LEAVING SAID WOOL ON THE ACID SIDE, AND (4) SUBSEQUENTLY PASSING SAID WOOL THROUGH AN AQUEOUS SOLUTION OF A SUBSTANCE TAKEN FROM THE CLASS CONSISTING OF ALKALI METAL SULFITE AND BISULFITE (5) AND AT A TEMPERATUE NOT OVER ABOUT 175*F. TO SENSITIZE SAID WOOL. 